1. Field of the Invention
The present invention generally relates to electrothermal fluid transducers and, specifically relates to transducers that smoothly and forcefully walk an object by myriad chaotic urgings.
2. Description of the Related Art
Applicant's copending application Ser. No. 07/807,667 filed Dec. 16, 1991 a continuation-in-part of Ser. No. 07/697,368 filed May 9, 1991 entitled Walking Expansion Actuator describes walking transducers that incorporate pulsed heaters that thermally pulse fluid to roll elements that affect forceful mechanical motions suitable for positioning an object by tractive walking. Microscopic and macroscopic embodiments of the apparatus are described, the former embodiment using a combination of epitaxial deposition methods to make both heaters and rolling elements, while the latter uses arts such as material forming and wire drawing. The described apparatus employs relatively intense and short electrical pulses in order to transduce the preponderance of the energy of an electrical pulse to mechanical work before the heat diffuses and mediates the thermal gradients necessary to affect a relatively high peak pressure. The apparatus is characterized by multiple heaters, each heater having a corresponding, essentially proximately, confined fluid portion, and by the mechanical summing of multiple mechanical transducer outputs.
Applicant's copending application Ser. No. 07/870,855 filed Apr. 20, 1992 entitled Thermal Urger comprises a multiplicity of small heaters arranged on a substrate surface proximate a fluid. An electrical heater pulse causes a short transitory thermal expansion pressure pulse in the immersing fluid. The pressure pulse propagates in and applies a transitory force to the fluid and to any co-immersed object. Pressure pulses have a character between that of a flowing fluid and an acoustic impulse. Cluster activation of heaters produces a prescribed temporal-spatial distribution of fluid pressure. Aperiodic activation of therger elements emulates a fluid force due to statistical gas molecule collisions. Embodiments of the present invention constitute electrically controllable fluid bearings, linear or rotary actuators and motors, acoustic transmitters and receivers, and modifiers of fluid boundary flow.
The animal class Echinoidea includes sea urchins, sea stars, and particularly the genus Ophiura (brittle sea stars), that walk sufficiently smoothly as to constitute gliding by the apparently chaotic activation of myriad tube feet. These animals glide smoothly in the senses that: smooth walking myriad feet need not entail rubbing and concomitant energy waste; and, walking accelerations are negligible. The sucking feet of echinoids, excluding the brittle stars, improve traction on slippery surfaces and in swift currents. The brittle star relies on the grips of myriad tiny "toes" in sea floor interstices. A typical echinoid has thousands of feet generally supported by and articulated from the pores of a madreporitic structure, typified by the underside pocked morphology of sand dollar and urchin shells. The glide obtains from a mechanical sum of forcible motional foot contributions, any one foot making relatively infrequent and fleeting contact with the sea floor. Echinoid walking may be compared to gas pressure.
The theory of statistical gas mechanics established that the microscopic activities of a collection of atoms or molecules causes the macroscopic effect measured as fluid pressure or force. Each molecule has a distinct velocity that changes after every collision. The average kinetic energy of molecules, and the average areal frequency density of molecular collisions with an impinged surface, is demonstrably the cause of the measurable macroscopic effect of gas pressure on that surface. Atoms or molecules lose no energy in the process of exerting pressure on the surface. The mean molecular kinetic energy does not run down with time, but is solely dependent on gas temperature, heat being the sustaining influence. Adding heat raises the temperature, speeds the molecules, and thereby raises the pressure. These principles are within the scope of the background of the present invention in the sense that the macroscopic effect (force, pressure, of feet) is causally related to the microscopic effect (kicks). An (imagined) improved statistical gas mechanics provides electrical remote control of the direction and speed of clusters of molecules (feet), so as to remotely produce predetermined temporal and spatial distributions of force exerted on the impinged surface of an object.
Entropy, in the context of the background of the present invention, is the measure of the inconvertibility of heat to work, and of the degree of disorderliness of apparatus component actions, both measures increasing with increasing entropy. Irreversibly dissipative transitory thermal processes (pulsed heaters), and myriad mechanical chaotic actions are considered entropic essences in the present context.